DESCRIPTION (Adapted from applicant's description): The proposal consists of six Specific Aims and the experiments that will achieve these aims. The aims are: 1. To determine the location(s) of G-CSF-R in the human placenta, at various stages of development, 2. To determine the function(s) of G-CSF in the human placenta, 3. To determine the location(s) of G-CSF production in the human placenta, at various stages development, 4. To determine the effect(s) of human intra-amniotic infection on placental production of G-CSF-R and G-CSF, 5. To quantify transplacental passage of G-CSF during term and preterm pregnancy in rats, and 6. To quantify transplacental passage of G-CSF during term and preterm normal and infected human gestations. The results will help clarify the location and function of placental G-CSF and G-CSF-R during human development, in health and during intra-amniotic infection, and the basic mechanistic events central to the pathogenesis of preterm labor and early-onset neonatal bacterial infection.